Dark Horizons
by Aini NuFire
Summary: Tag to the season 10 finale, because I can't abide that cliffhanger for the next four months. SPOILERS. One-shot


**A/N: That finale was brutal. So here's how I relieved my angst over whether our beloved angel and king of Hell survive. And the Winchesters. SPOILERS if you haven't watched the last few episodes of season 10.**

* * *

 **"Dark Horizons"**

There it was again. That bloody ringing. It vibrated in his ears, his head, hell even the cold cement floor currently serving as a rather uncomfortable bed. Why couldn't it just shut up? Ah, finally, silence again. Crowley let himself drift in the blackness between waking and unconscious oblivion…

Until the blasted chiming started up again. He pried his eyelids open, the world around him dim and blurry. With great effort, he pushed himself up onto one elbow—the one that was not throbbing. Gray smudges solidified into stone walls, barely suffused with pale light peeking through narrow windows near the ceiling. An overturned table lay splintered a few feet away, herbs and leftover spell ingredients scattered across the floor.

Crowley scowled as he managed to lift himself upright, one hand shooting up to brace his left shoulder. Hot stickiness ebbed against the pressure, and he gritted his teeth. That bloody wretch would pay for this. Trying to take out the _King_ of Hell. By siccing a _crazed angel_ on him! Speaking of said angel… Crowley roved his gaze to the side where a familiar trench-coated figure lay, out cold on the concrete. Dried blood tracks like veins spread out from closed eyes. The silver angel blade glinted halfway between them, drenched in coats of both demon and angelic blood. The ringing, which was splitting Crowley's head like a pneumatic drill, was coming from the trench coat's pocket.

Muscles taut with anticipation in case zombie-Castiel happened to wake up—unlikely if the incessant cell phone hadn't accomplished it yet—Crowley reached into the pocket and pulled out the vibrating cell. He swiped the screen to answer, scooting back to slouch against the wall.

"Dean Winchester," he drawled. "I hope you are now without a certain Mark, or this all would've been for nothing."

"…Crowley? What the hell are you doing with Cas's phone?"

"Castiel can't talk right now."

"Why not? I've been calling for the past half hour. What the hell happened over there? Do you have any idea what you've done?"

Crowley held the phone slightly away from his ear while the Winchester ranted. "I take it the Mark is in fact gone. Congratulations."

"Dammit, Crowley!" Dean growled. "The Mark was some kind of lock and key, and with it gone this thing called the Darkness is now free. Have you even looked outside?"

"I've been a bit busy nearly getting killed by your boyfriend," he snapped back.

"What? Where's Cas?"

Crowley shifted his gaze to the prone angel and the oily puddle of crimson pooling from his side. He dropped his head back against the wall with a sigh. "My _mother_ , whom I will disembowel and stuff her intestines down her throat the next time I see her, cast a voodoo spell on Castiel, turned him into a bloody attack dog. Foaming at the mouth and all. He nearly killed me, by the way."

Dean's voice lowered an octave. "What did you do?"

"Defended myself," he retorted indignantly. "Don't worry, your wingman is still alive." Crowley canted his head. "I think."

"Where's Rowena now?"

"Who knows. She took the Book of the Damned and fled."

There was a tense silence on the other end before Dean spoke again. "We're almost there."

The line clicked, and Crowley moved the phone to look at the darkening screen. "No rush," he muttered, and let the cell clatter to the ground. He glanced up at the gloomy windows, noting with a vague frown that it seemed rather dark for three in the afternoon.

* * *

Dean hung up and tossed the phone on the seat. "This is just great, Sam. Rowena has the Book of the Damned, did something to Cas on her way out, and now 'the Darkness' is taking over the world." His fingers cramped around the steering wheel as the Impala roared down the highway. The horizon was coated in a filmy brume that turned the sky blood-orange. It wasn't as opaque as storm clouds, more like smoke from a massive fire rising to blot out the sun.

After that heart-stopping moment when the Darkness had enveloped them, Dean thought they'd finally punched their number. But the hurricane had passed, only to bleed into the sky and begin to churn like a simmering squall. Maybe it wasn't strong enough to plunge everything into total darkness, but as the light steadily waned, it sure seemed like the initial mantle was thickening.

Sam was quiet for a moment in the passenger seat. "Look, I know this is bad, and I'm gonna do everything in my power to fix it. But I'm not sorry for getting the Mark off you, Dean. I'll never be sorry for that."

Dean rolled his neck. With the Mark gone, he was finally able to think clearly without the influence of rage and bloodlust. Yeah, he was still royally pissed that Sam had gone behind his back, had pursued a cure even when they knew the cost was too much—and really, they didn't even know what all this cost entailed yet—but being himself again…there was such relief, like a monumental weight had been lifted off his shoulders. Besides, he could have prevented this himself…if he'd been willing to sacrifice Sam, either by killing him or sharing the Mark with him. Either way, it would have been a death sentence. And Dean hadn't been able to go through with it, not even under the Mark's influence. So yeah, he knew where his little brother was coming from.

That didn't change that they'd probably brought about the end of the world. Again.

"The only one I have to blame is myself," he said around a gravelly throat. "But I'm gonna fix it. We're both gonna fix it." Somehow. Except the one person left on this planet who might have inside information on the Darkness was apparently out of commission. Crowley hadn't been very clear on what happened to Castiel, and fear made Dean press harder on the gas.

The Impala revved down the road as Dean took the turns Sam directed in order to get to the place he'd been stashing Rowena while she decoded the Book. Even though Crowley had said the witch was long gone, Dean still pulled out his pistol and held it at the ready as he entered.

The place was dark and musty, the tang of blood and charred elements heavy on the air. Dean descended the steps warily, gaze snagging on the body of a young man, throat gouged. An image of the kid Dean shot back in the bunker flitted through his mind, this time carrying the crushing weight of guilt the Mark had protected him from before. He shoved it down; there wasn't time for that now.

Movement to his left had Dean swinging the gun up and landing on Crowley. The King of Hell was slumped wearily against the wall, one hand clutching his shoulder as blood leaked between his fingers. Dean started forward, but then he caught sight of tan and black slacks a few feet further, and his heart plummeted into his stomach. Stashing his gun, Dean leaped over the debris and dropped down next to Castiel.

"Cas?" He braced the angel's face, gut twisting at the bloody streaks running from his eyes. Dean had seen that before, with those girls Rowena had recruited and then sacrificed so she could get away when the Winchesters first encountered her. "Cas, wake up! Come on, buddy."

"Oh my god," Sam uttered behind him.

" _I'm_ fine, by the way," Crowley's grating voice cut in. "It's not like he didn't stab me or anything."

Dean shot him a scathing look, still cradling Cas's head. When he turned back, he noticed the cold liquid seeping into his pant leg, and glanced down at a puddle of blood oozing from a hole in Castiel's side. He swore, and quickly fished out a handkerchief from his pocket to press against the wound.

For a split moment, Dean's mind flashed back to beating Cas to a bloody pulp, to angling the angel blade above his throat. He shook himself out of it. "You son-of-a-bitch," he growled, though wasn't sure whether he meant Crowley or himself.

"Hey, it was self-defense! And you'll note that I did _not_ kill him, despite him not returning the favor."

"You said Rowena cast a spell," Dean gritted out.

"Yes," Crowley scowled. "Which is why I won't hold this against him."

Sam swept his gaze over the mess. "What the hell happened?"

Crowley shifted to sit up straighter. "She must have cast a dual spell, something to boost her power while simultaneously removing the Mark. Once she completed the casting, she managed to trap us both before turning dear old Castiel into a rabid dog."

Dean shook his head. That spell had killed those girls after it'd run its course. Cas was an angel, and obviously wasn't dead (no burned wings on the ground), but what kind of damage would it have caused?

"Sam, help me get him to the car." The sooner they got back to the bunker, the better. Hopefully it was well-protected against the Darkness…even if it was a primordial evil not even the Men of Letters would have heard of before.

Sam knelt on the other side of Castiel and hefted one arm over his shoulder while Dean did the same. Together, they hauled Cas off the floor, his head lolling limply to the side.

"Can you walk?" Dean asked Crowley as they shuffled past him.

The King of Hell huffed, but pushed himself up with strenuous effort.

"Dean, what the hell," Sam blurted, shooting a tense look at Crowley.

"What? We have an evil older than God and Hell and demons running around; we need all the help we can get."

"Right, I'm not clear on what the hell you were talking about before," Crowley interjected. "The Darkness? Sounds like a cheesy death metal band."

"In the car," Dean barked, and started moving again. They got outside, and damn if it didn't seem darker already. Scientists were probably in an uproar, claiming that the sun was collapsing into a black hole or something.

Crowley paused on the threshold, expression for once slack with stupefaction. "Well, this does look a mess."

"Just get in." Dean dropped Cas into the backseat, and Sam went around to the other side to pull the angel all the way in.

"I'm not sitting next to Cujo. Suppose he wakes up and tries to eat me again?"

Dean rolled his eyes. "Then sit up front. Sam, here." He tossed his brother the keys, which Sam fumbled to catch.

"What? Dean, you can't be serious." Sam's eyes kept flicking nervously to Crowley.

Dean popped the trunk of the Impala and pulled out a first aid bag, then slammed it shut. "You know what, I don't know what the hell is going on between you two—"

"Moose tried to kill me the other day," Crowley broke in helpfully.

"Well stow it," Dean snapped. "We've got bigger problems." With that, he climbed into the backseat and began unpacking the medical supplies.

A few moments later, both Sam and Crowley slipped into the front. Sam started the ignition, and with a rumble from the engine, pulled back onto the road.

"So," Crowley spoke up after a prolonged period of silence, eyeing Sam's blossoming bruises curiously. "Who's going to fill me in?"

Dean glanced up to meet his brother's gaze in the rearview mirror. He hadn't explained everything Death had told him yet, as they'd first been too busy running for their lives, and then too stunned and freaked out to have much of a debrief.

Dean ripped open a patch of medicated gauze and began to tell all he knew. Which, granted, wasn't much. He finished bandaging Cas's stomach by the time he'd relayed everything Death had said.

"Well," Crowley finally spoke. "That would have been nice to know _beforehand_." He shot a seething look at Sam, who rolled his shoulder in response.

"Yeah, and it probably would've been better if I hadn't ganked Death, the one guy who could tell us what the Darkness really is, and how to contain it," Dean put in. He ripped open a second patch of gauze and reached between the seats to slap it against Crowley's shoulder, eliciting a pained yelp. "Look, we're in this shit-hole now, so let's forget about how we got here and concentrate on getting out." Uncapping a water bottle, Dean poured a bit onto a piece of cloth and began wiping the blood from Cas's face.

Sam cleared his throat nervously. "If the Mark was the lock holding this Darkness at bay, then someone needs to take it on again."

Dean didn't look at his brother. Part of him believed that was his responsibility. After all, he'd set this domino effect into motion by willingly taking the Mark from Cain. But another part of him was terrified to go back to that dark place. It was like Hell all over again—he'd become the thing he most hated.

"Cain is dead, and the only other living being who has that power is locked in the Cage," Crowley pointed out.

"Lucifer," Sam breathed, a touch of fear in his voice.

"Putting the lock back in place is only part of the solution," Dean broke in, voice rough with barely constrained emotion. "First we gotta figure out how to trap the Darkness to begin with." And damn if that didn't seem impossible. _God_ was the one who'd battled the Darkness way back when. And he sure as hell wasn't reliable.

A faint groan jerked his attention to the angel next to him, in time for Dean to see Castiel's face grimace.

"Cas? Open your eyes." He cupped one side of Castiel's neck, holding his head steady against the vibrating car.

Crowley pressed himself against the door panel. "You might want a weapon handy."

Sam took his foot off the gas and eased the Impala onto the side of the road. Shifting into park, he twisted around to see between the seats, jaw tight and expression worried.

Dean tightened his grip on the angel. "Come on, man, show me you're still in there."

"D'n…" a frail rasp issued from parched lips.

"Right here. Look at me. That's it."

Dark lashes fluttered, revealing bloodshot eyes glistening with pain and confusion…and fear. Dean felt as though he'd been sucker punched, that glazed look all too similar to how Cas had looked at him the last time they'd been face to face.

"Cas?" Sam called worriedly.

"Wh…" A choked gasp cut off his voice, and Cas's face screwed up as he almost wrenched back to knock his skull against the window, but Dean's hand cupped the side of his head firmly. One arm weakly moved to his stomach.

Dean reached out with his free hand to clasp Castiel's fingers before the angel accidentally poked the wound. "Easy, Cas, easy. Take a breath, you're gonna be okay." Because as long as he was awake and recognized them, he'd be _fine_ , dammit.

Cas's shoulders shuddered with the effort it took to inhale and exhale deeply, but after a few of those, he cracked his eyes open again. "What…where…"

"We're on our way back to the bunker," Sam answered.

"Do you remember what happened?" Dean asked.

Exhausted blue eyes slowly lolled up to meet his. "I…Dean…are you?"

"I'm good." He let go of Cas's face to roll up his sleeve. "Mark's gone."

"Oh, good…" Cas slumped further into the seat.

"What, don't you remember trying to gouge my eyes out?"

"Crowley," Dean growled in warning, then softened his tone toward the angel. "Cas, hey, don't clock out on me now. I need you awake."

Cas turned his head, eyelids sluggishly dragging open, and then a flicker of alertness flashed across his face. "Rowena, where?"

"Bitch got away."

Cas squeezed his eyes shut again. "I'm sorry."

"Wasn't your fault. She put some kind of whammy on you. But you're okay now." Dean swallowed hard. "Right? You're okay?"

Cas's brow furrowed, and he winced again. "I think…getting blown apart by an archangel…hurt less."

"Fair chance," Dean agreed. "You're pretty beat up, but we'll get back to the bunker and patch you up. Sam?" At a nod from him, Sam shifted the car into gear and pulled back out onto the road.

"Um, Cas," Dean started. "You ever heard of the Darkness? The thing God battled and defeated before he created the world?"

Cas frowned. "That…is…a very old tale. Only the archangels were present at that time."

"So you never fought the Darkness?" Dean pressed, exchanging a silent look with Sam in the mirror again. Damn, he'd really been hoping Cas would know what to do with this.

"Before…I was created," he wheezed, and then coughed, arm curling protectively over his side.

Dean grasped his shoulder. "Easy, okay."

"Why?" Cas managed to angle his no-nonsense, angelic warrior look at Dean, which made him feel marginally better that his friend would be okay after all.

"The Mark was apparently the lock keeping the Darkness trapped somewhere. And now that it's gone…"

Cas's facial muscles slackened in surprise, and he let out a sharp exhale. "Of course. Lucifer's Mark… I…we all knew he was entrusted with the lock and key, we just didn't know what form it had. So…" Cas craned his neck to look out the window at the sanguinary sky. "Oh no."

"Yeah," Dean echoed. "So, uh, I don't suppose you know how we fight this thing?"

Cas looked back at him, expression pinched, and gave a small head shake.

"Right, well, we've faced impossible odds before. We can do it again."

Crowley let out a snort from the front seat, but Dean ignored it. Instead, he locked gazes with Sam through the mirror once more, each silently promising that they'd stick together on this. That was how they'd always triumphed in the past. And yeah, maybe this was the end of the line, the final battle that would finally claim them. But after years of sacrificing others, maybe it was their turn to take the hit, to right all the wrongs they'd committed. And they could do it. Him, Sam, and Cas—the three of them had always been enough.

And then of course there was the King of Hell, who wasn't a bad player to have in their corner on this. Yeah, they'd figure it out. Time for one last ride.


End file.
